DESCRIPTION: (Applicant's Abstract) The reported adverse effects of marijuana use, its growing availability and consumption in recent years have heightened public concern. The national debate between those pressuring for its legalization and those supporting its ban will continue until the adverse and beneficial effects of this drug are clearly defined. One of the major concerns, among many central and peripheral effects of habitual marijuana smoking or exposure to cannabinoid derivatives, is their reported adverse effects on reproductive functions, including retard embryonic growth, pregnancy failure and poor fertilizing capacity of sperm. The mechanism(s) by which these cannabinoid effects are mediated are poorly defined. Recent identification and cloning of G-protein coupled cannabinoid receptors in the brain (CB1-R) and spleen (CB2-R) provide evidence that many of these effects are mediated via these receptors. Further, a putative endogenous cannabinoid ligand, arachidonoylethanolamide (anandamide) has been detected in the brain. Our recent finding of expression of cannabinoid receptors in the preimplantation mouse embryo and uterus, as well as anandamide synthesizing capacity in the uterus and oviduct also place these tissues as targets for cannabinoid ligand-receptor signaling and prompted us to continue investigation on this signaling pathway during early pregnancy. Our specific aims are to determine in the mouse: (1) Expression and regulation of the CB1-R and CB2-R genes in the embryo and uterus during early pregnancy (days 1-8), (2) Anandamide synthesizing and (3) Anandamide hydrolyzing capacities, and their regulation in the oviduct and uterus during this period and under steroid hormonal stimulation, (4) Status of phospholipase A2 and phospholipase D activities in these tissues under these conditions, and (5) Roles of cannabinoid-ligand receptor signaling in the embryo and uterus during early pregnancy. We will use multiple experimental approaches including reverse transcription-polymerase chain reaction (RT-PCR),l Northern blot and in situ hybridization, immunostaining, Western blotting, autoradiographic and Scatchard analysis of ligand binding, enzyme assays, embryo culture and transfer, and others to accomplish our goal. Since there are similarities between mouse and human preimplantation and implantation physiology, results of this investigation will further our knowledge that should be valuable for defining marijuana's role in women's health issues.